Guilty Gear was first released in Japan on May 14, 1998 for the PlayStation.[1] It takes place around the year 2180, in a chaotic, mystical future world. In 2010, mankind discovered an unlimited energy source of incredible power, which was labeled magic. Despite providing a solution for world energy crisis, wars continued. The power of magic was combined with humans and other creatures creating living weapons known as "Gears". Eventually, the Gears turned on the human race, beginning a century-long global war known as the Crusades where the Sacred Order of Holy Knights (聖騎士団,Seikishidan?), defeated Justice, leader of the Gears. With Justice having been locked away in a dimensional prison, all other Gears seemingly ceased to function, bringing end to an age of conflict. Five years after the war's end, a Gear called Testament planned to free Justice. In response, the United Nations heralded a tournament of fighters capable of defeating the resurgent enemies, Testament and Justice. Ultimately, a bounty hunter named Sol Badguy defeated Justice, giving way to another uneasy peace.

Guilty Gear X was first released in Japan on July 2000 for the arcades as a sequel to the first game.[1] Less than a year later, reports of a newly discovered commander Gear surfaced. Fearing the dawn of another war, the United Nations held a tournament, offering 500,000 World Dollars for the destruction of the Gear. The Gear was a girl named Dizzy, who, while very powerful, lacked a desire for war and unnecessary destruction. She was defeated, but her life was spared by Sol Badguy. Soon, though, she was found by Ky Kiske, the charismatic police chief of the United Nations and ex-chief of the Sacred Order of Holy Knights. He entrusted her care to Johnny and May, the leader of the Jellyfish Air Pirates, who welcomed her as one of their own. Jam Kuradoberi, a bounty hunter and struggling chef, claimed credit for Dizzy's disappearance so she could collect the reward and finance her restaurant.

Guilty Gear X2 was first released in Japan on May 23, 2002 for the arcades as the third game in the series.[1] The time following Dizzy's disappearance, the mysterious Post War Administration Bureau began secretly investigating the Gears and fighters from previous tournaments for their own needs and ambitions. Various powers were working in the shadows to gain control of the world, one being the very creator of the Gears, a mysterious figure known only as "That Man". Fighters find themselves in a reality beyond their control, most notably in the manipulative hands of the villainess I-No, who is revealed to be a servant of That Man.

Guilty Gear Petit was first released in Japan on January 25, 2001 for the WonderSwan, and spawned a sequel, Guilty Gear Petit 2 released on the September 27 of the same year also for the WonderSwan.[1] Being a small spin-off, the games are not part of the mainline series.

Guilty Gear Isuka was first released in Japan on December 17, 2003 for the arcades, and is the fourth game in the series. The title was ported to PS2, Xbox and Windows.[1]

Guilty Gear Judgment was first released in Japan on August 24, 2006 for the PlayStation Portable.[3] A week has passed without any word from the small Eastern European kingdom of Villtania. However, as refugees are found, the United Nations becomes aware of devastation and ungodly experiments conducted by Villtania's leading sorcerer and scientist, Raymond. As a result, the United Nations declares an international emergency and promptly offers a reward to anyone who can stop Raymond and bring order back to Villtania. A large gathering of warriors attracted to earning the bounty soon fight to decide who will challenge Raymond.

Guilty Gear 2: Overture was first released in Japan on November 29, 2007 for the Xbox 360.[4] Set five years after Guilty Gear, Humanity created the Gears, biological weapons based on an endless energy called divine power. But one of the Gears went berserk, declared war on humanity, and started a terrible war. In response, mankind formed an order of elite knights, ending the Gears' reign of terror. It seemed that peace had been restored. But true history has yet to reveal itself, until now, in Guilty Gear 2: Overture. It is the first entry in the series to use 3D models instead of sprites, and is not a traditional fighting game. Despite this change in genre, the game's story is canon and the game is considered part of the mainline series.

Guilty Gear Xrd, set in 2187, one year after the events of Overture, was released on February 20, 2014 in Japanese Arcades, December 4, 2014 for PlayStation 3 and PlayStation 4, and received a digital release over Steam on December 10, 2015 for Windows. It is the second entry in the series to use 3D models instead of sprites, the third under the X title, and the 8th mainline title overall.[6]

Guilty Gear consists primarily of one-on-one competitive battles. Players are tasked with depleting their opponent's life gauge by utilizing attacks unique to each playable character. In the case of timed matches, the player with the most remaining life when time runs out is the victor of that round.

Guilty Gear Isuka prominently allowed up to four simultaneous players in battle, as well as the option to divide the characters into teams. It also eschewed the typical multiple-round format in favor of each player having a limited stock of "souls". Depleting a player's life gauge decreased their stock of souls and temporarily incapacitated them, and each remaining soul allowed a player to return to battle with a full life gauge. They would be defeated for the rest of the match if their life gauge and souls were both exhausted. These features have not returned for subsequent games.

Each game in the series includes a "Tension Gauge" that fills as the player performs offensive maneuvers, such as approaching the opponent or attacking them. Portions of the Tension Gauge can be expended to perform various techniques. Each character has at least one Overdrive, special attacks that can deal extensive damage to an opponent or bolster aspects of the user, like speed or attack power. "Faultless Defense" allows players to prevent "tick damage", damage received from normally guarding against special attacks, at the expense of the Tension Gauge. Guilty Gear X and later titles introduced more advanced techniques involving the Tension Gauge, such as the "Roman Cancel", allowing players to immediately stop the remaining animation of an attack, and "Dead Angle Attacks", counterattacks performed while a player is guarding.

The Tension Gauge is also tied in with the usage of "instant kill" techniques (一撃必殺技,ichigeki hissatsu waza?), high-risk attacks that are difficult to connect with but instantly inflict death on the opponent regardless of the amount of life remaining. In Guilty Gear, these attacks ended the entire match if they successfully hit the opponent, but this was toned down in later games by ending the round instead. Failing to connect with the technique penalizes the user by removing the Tension Gauge and its related uses for the rest of the round.

Guilty Gear X2 introduced a "Burst Gauge" that slowly fills during the progression of a match. When completely filled, players can perform a "Psyche Burst" in an attempt to quickly stop an opponent's offense, even knocking back the opponent if they are close enough. This mechanic has also appeared in some form in other Arc System Works games, such as BlazBlue and Persona 4 Arena, as well as other fighting games such as Skullgirls.

Many characters also feature their own unique mechanics that differentiate them from each other. For example, Zato-1 utilizes a shadow-like symbiotic creature named Eddie that is able to detach itself and be controlled separately for a period of time, allowing complex tandem attacks between the two. Venom can set out weaponized billiard balls on screen that can be projected in various directions depending on how the player strikes them with certain attacks. Johnny carries a limited set of coins that can be thrown at the opponent. Though the coins themselves deal little damage, each successive hit strengthens his "Mist Finer" technique to incredibly powerful levels.

In addition to the Guilty Gear video game series, other products were also released. Two novelizations of Guilty Gear X were written by Norimitsu Kaihō, illustrated by the own Daisuke Ishiwatari, and published by Enterbrain: Lightning the Argent(白銀の迅雷,Shirogane no Jinrai?), and The Butterfly and Her(胡蝶と疾風,Kochō to Hayate?), on January 20, 2001 and on August 24, 2002.[22][23] A manga titled Guilty Gear Xtra(ギルティギアXTRA?), a collaboration among Daisuke Ishiwatari, Norimitsu Kaihō, and Akihito Sumii, was serialized in Kodansha's Magazine Z on September 22, 2003.[24] Studio DNA and Enterbrain also published comics anthologies.[23][25] Several drama CDs were published; Scitron released a series of two drama CDs—Guilty Gear X Vol. 1 and Vol. 2—between October 24, and November 24, 2001,[25] and two series of drama CDs based on Guilty Gear X2 were released by Team Entertainment: Red and Black—a series— were released in 2003 between July 16, and August 20.[23] Another series of drama CDs, Night of Knives, was published in three volumes between October 20 and December 22, 2004.[26][27] Also action figures, guidebooks, and a trading card game series based on Guilty Gear were released.[23][25]

The Guilty Gear PlayStation disc has a hidden song that can be played on a computer by opening the sound file "OBJ_" and skipping to track 2.[citation needed] The song repeats after 1:13 and loops a few times.

Guilty Gear is considered by several sources to be the greatest 2D fighting game.[79][80][81]GameSpot said that "Guilty Gear is one of the few non-Capcom or SNK 2D fighters to make any sort of impact on the genre",[82] while Eurogamer stated: "If 2D beat-em-ups are moving toward extinction, they really are ending on a high note with stuff like this."[83] Its sequels were also well received. GameSpy said "Guilty Gear X is hands-down the best 2D fighting game to date",[84] and Guilty Gear X2 was described by About.com as "easily the best 2D fighter to come around in a long time."[85]

In 2012, Complex ranked Guilty Gear at number 47 on the list of the best video game franchises, commenting: "Where other fighters were moving toward realism and more down to Earth physics and combos, Guilty Gear was content to turn those notions on their head, paving the way for the more chaotic fighters we're seeing today."[86]Yahoo! Voices' editor S.W. Hampson included Guilty Gear among the 10 best fighting game franchises of all time, praising the series's evolution along the years, the "distinctive visual flair" of its 2D sprites, and the "well-defined story lines", adding "its identity is among the most unique in the world of beat-'em-ups."[64]

^Dunham, Jeremy; Sulic, Ivan; Lewis, Ed (July 14, 2004). "Dirty Dozen: Hidden Gems". IGN. Ziff Davis Media. Retrieved August 3, 2013. In fact, in many ways Guilty Gear X2 is one of the prettiest games on the PS2. Not necessarily because of its technology or its art style [...], but because of how well all of its visual elements come together. What truly makes it fantastic, though, is its fast and furious fighting engine and strong opportunity for strategy. In short, it's everything a 2D fighter should be.CS1 maint: Multiple names: authors list (link)

^Ingenito, Vincent (December 7, 2012). "Guilty Gear XX Accent Core Plus Review". IGN. Ziff Davis Media. Retrieved August 3, 2013. Much like the guitar virtuosos providing the game's stellar soundtrack, Guilty Gear players are known for their uncompromising technical prowess. [...] Controls are responsive, and the wide array of mobility options and flashy moves for each character can be appreciated within minutes of picking up the controller. [...] For as varied as the 25 characters look, their play styles are even more divergent.

^Goldstein, Hilary (September 10, 2004). "Guilty Gear X2 #Reload". IGN. Ziff Davis Media. p. 2. Retrieved August 3, 2013. What really separates Guilty Gear from the rest of the crowd are the absolutely bizarre characters. [...] each character is a very distinguishable entity. [...] There are more than 20 of these characters and they are all just as interesting

^Sell, Chris (December 30, 2004). "Guilty Gear X2 Reload Review". PALGN. Retrieved August 3, 2013. The special combos are incredible and range from fairly simple to very advanced. The payoff is always rewarding both in damage and in insane visuals.

^Turner, Benjamin (February 5, 2003). "Reviews: Guilty Gear X2". GameSpy. IGN Entertainment. p. 1. Archived from the original on May 21, 2009. Retrieved August 1, 2013. At the game's core is a very solid fighting engine that's been refined since the last game.

^Turner, Benjamin (February 5, 2003). "Reviews: Guilty Gear X2". GameSpy. IGN Entertainment. p. 2. Archived from the original on May 21, 2009. Retrieved August 1, 2013. Groundbreaking and triumphant. Lesser words just don't do justice to the superior graphics and general aesthetics of Guilty Gear X2. X2 is easily the most beautiful 2D game yet crafted, and should prove to anyone with a working cerebrum that 2D is not inferior to 3D [...] High-resolution graphics would be fairly pointless if the actual art were mediocre, so it's a good thing that Guilty Gear X2 has some of the coolest character designs ever seen in a game. [...] The hard-rocking soundtrack is almost as impressive.

^Nelson, Randy (November 11, 1998). "Guilty Gear". IGN. Ziff Davis Media. Retrieved August 3, 2013. If you consider yourself a fighting connoisseur, it comes highly recommended. No true fan of the genre should be without a copy.

^Fudge, James (December 22, 2001). "Reviews: Guilty Gear X (PS2)". GameSpy. IGN Entertainment. p. 1. Archived from the original on February 18, 2005. Retrieved August 3, 2013. Guilty Gear X is hands-down the best 2D fighting game to date. [...] The three key factors that brought me to this conclusion are eye candy, fast and furious fighting and interesting (albeit over-the-top) characters. [...] As with most sequels GGX brings a number of new things to the table, like extra moves, improved graphics and a few new token characters.